Week 6-Learning Flashcards
What are the two forms of NON-ASSOCIATIVE learning?
Habituation: DECREASE in the strength or occurrence of behaviour due to the REPEATED EXPOSURE to the stimulus that produces that behaviour
e.g., getting used to the noise when living at a busy street
Sensitization: INCREASE in the strength or occurrence of behaviour due to exposure to an arousing/unpleasant/noxious situation
e.g., being increasingly annoyed by the lecturer saying ‘okay’ after every sentence in a boring (but not in an interesting) lecture
How does Habitation/sensitization occur?
- Decrease / Increase in sensitivity of sensory receptor (an adaptation of stimulus-perception changes)
- Decrease / Increase of motor response(behavioural)
- Difficult to distinguish based on observation of behaviour alone
- Need to look at simple neuronal circuits
Invertebrate Models of Learning
What is Aplysia Californica?
(Most commonly used model of learning-Less ethical dilemmas)
Aplysia Californica: Intensively studied by Eric Kandel because of a very few but giant neurons that could be easily isolated to form ‘mini-brains’
How has non-associative learning been studied?
Non-Associative Learning in the Aplysia
Gill withdrawal is the most studied reflex in Aplysia C.
stimulation of the siphon leads to a protective/defence reflex to withdraw the gill only two neurons involved.
What are the two forms of CLASSICAL CONDITIONING?
Classical Conditioning-Pavlov
Learning that two events occur together.
Any stimulus can become CS (in contrast to sensitisation, only emotional threatening stimulus)
Instrumental/Operant Conditioning-Skinner & Thorndike
Two types of Procedural Learning
Associative-Classical Conditioning; Operant COnditioning
Non-associative- Habituation, Sensitization
What two mechanisms occur within the hippocampus?
Two important mechanisms, long-term potentiation (LTP) and long-term depression (LTD) have been discovered to take place in this structure (but also in other brain structures). LTP and LTD in the hippocampus and their role for learning.
What is the role of the hippocampus in the vertebrate model of learning(Declarative memory)
Hippocampus involved in the formation of new memories crucial structure for declarative learning
- Long-Term Potentiation
- Long-Term Depression
- CREB mediated protein synthesis
How does Long Term Potentiation (LTP) occur?
Long-Term Potentiation occurs with high-frequency stimulation of Schaffer collaterals
(CA1 & CA3- Schaffer collaterals between these two)
LTP & LTD
-LTP and LTD are crucial mechanisms underlying
synaptic plasticity especially in the hippocampus
-LTP is triggered by high frequent (synchronous AP) -stimulation depolarised postsynaptic membrane AND
glutamate binding to NMDA receptor
- new AMPA receptors (sodium channels) are incorporated into the postsynaptic membrane
- more sodium channels –> easier to activate postsynaptic neuron –> more efficient synapse
How does Long Term Potentiation (LTP) occur?
Long-Term Potentiation occurs with HIGH-frequency stimulation of Schaffer collaterals
Brief, high-frequency stimulation > 10 Hz (10 AP/sec) (larger than 10Hz) LONG TERM BETWEEN 2 SYNAPSES.
LTP Duration:
Hippocampal slices: 40 hours
Intact animals: Up to a year
(CA1 & CA3- Schaffer collaterals between these two)
How does Long Term Depression (LTD) occur?
Long-Term Depression occurs with LOW-frequency stimulation of Schaffer collaterals
Without strong NMDA receptor activity
-weak influx of calcium
-AMPA receptors are lost
-synapse becomes less effective: Long-term depression LTD
How are long term memories formed?
LTP after repeated paired input leads to -new AMPA receptors, - protein synthesis, -up-regulation of gene transcription via phosphorylated CREB-1 The latter two triggers synaptic growth!
(LTP has immediate long term effects)
What does the addition of protein inhibitors do?
Reduces Long Term Memory
Knockout mice poor object placement recognition
